German OS No. 23 12 756.2 already discloses a milking cup having a rubber teat holder, in which from an underpressure relief valve which is provided on the milking cup air can flow into the space of the rubber teat holder below the teat. In this milking cup the pipe or tube, which extends from the underpressure relief valve to the suction sleeve, is constructed in one piece with the rubber teat holder and the pipe ends inclined with respect to the axis of the suction sleeve into said suction sleeve. Through this it is achieved that during cleaning of the milking cup, if same is turned upside down, milk flows into this pipe, which leads to the underpressure relief valve, and solidifies there as cheese. Since one can usually not look into the milking cup, these residues are not noticed and can cause the quality of the milk which is later obtained with this milking cup to be affected as well as the entire function of the underpressure relief valve being affected or even completely turned off. The loss of the operation of the underpressure relief valve cannot easily be determined.
U.S. Pat. No. 3,255,732 already discloses a milking cup having a rubber teat holder, in which an additional connecting tube, which terminates approximately at a right angle in the suction sleeve, is formed out directly in one piece with the rubber teat holder. Also in this milking cup occur the already above-mentioned disadvantages of an unnoticed contamination of the supply pipe to the underpressure relief valve. In this known arrangement the pipe which ends in the suction sleeve of the teat rubber must additionally also be guided out through the sleeve-like cup of the milking cup to the outside, which brings about an extremely complicated installation of the rubber teat holder and thus an extremely difficult replaceability of the rubber teat holder. This also makes more difficult the weekly general cleaning operation of the milking cup, as is generally common, and during which the milking cup is disassembled. Furthermore, however, this connecting pipe or tube is subjected to special stresses in as far as, on the one hand, the tube is held fixedly in the cup, while on the other hand the rubber teat holder is being moved back and forth constantly during the milking operation.
Therefore, the basic purpose of the invention is to produce a simple milking cup having a rubber teat holder, in which the relieving air can be introduced into the space below and teat and which permits a simple maintenance of the cleanness of the parts.
This purpose is attained inventively by utilizing a milking cup of the above-mentioned type and locating the end of the tube a ways into the suction sleeve or a member secured to the suction sleeve.
Through this construction, an important advantage is achieved in that a maintenance of cleanness is made substantially easier. In particular, the difficulties which have occurred up to now with respect to the milk residues in the tube leading to the underpressure relief valve are overcome completely.
As particularly advantageous was found an embodiment in which the end of the tube, which projects into the suction sleeve or joint member secured to the suction sleeve, is constructed in form of a drip projection. In particular with respect to any easy cleaning possibility it has also proven to be advantageous to releasably connect the tube to the suction sleeve or to the joint member which is connected to the suction sleeve. In particular, in such a development, additional expenses can be avoided, which can result from forming a one-piece rubber teat holder and tube construction.
It is easily possible to permit the tube to terminate also directly below the teat in the suction sleeve. Especially in such a position of the mouth of the tube, the invention is of a special value, because in this case the condition of the tube, which leads to the underpressure relief valve, can be controlled without particular difficulties. On the other hand, however, especially in this position of the mouth of the tube, two further advantages are gained. One, the teat can be relieved substantially from the underpressure, whereby at the same time sufficient massaging can be carried out, and two, the milk transport problem is solved at the same time in an entirely surprising manner. Because through the air, which during the relief cycle right after the milk flow from the teat stops, flows into the lower and underpressure in the suction sleeve, a discharge of the milk through the discharge vacuum pipe is simultaneously effected without problem. Due to the fact that the relief air is introduced practically directly below the teat, a back injection of milk into the teat does not occur, which up to now has often been a reason for undesired utter infections.
As a whole, a quick milk transport at a reduced cross section of the milk discharge pipe is achieved.
If one permits according to a different embodiment of the invention the tube to extend on the outside of the sleeve-like cup and to terminate in the part of the suction sleeve projecting from the cup or the joint member outside of the cup, then here the important advantage is obtained that the tube can be kept clean particularly well and, if it preferably consists of a transparent material, its cleanliness can also be supervised.
For a maintenance of the cleanliness, it has also been proven to be particularly advantageous to arrange the underpressure relief valve at a point of the cup which is as close as possible to the end of the suction sleeve, which end exits from the cup, or the joint member, so that the length of the tube can be as short as possible.
In order to be able to easily observe the mouth end of the tube for the collection of any residues, which end projects into the end of the suction sleeve projecting from the cup or a joint member, the part of the suction sleeve which projects from the cup or the joint member is preferably manufactured of a transparent material. A further advantage is thereby simultaneously obtained that the perfect functioning of the underpressure relief valve can be controlled or supervised easily during the operation. Because in this case the air, which shoots through the underpressure relief valve and the tube into the inside of the suction sleeve or the joint member, will blow the impact surface free of milk, which can be observed easily.
To reduce the danger of milk running into the mouth of the tube, it has been proven furthermore to be advantageous to enlarge the cross section of the suction sleeve or of the joint member at least at the level of the mouth of the tube compared with the cross section of the milk discharge pipe.
According to a different solution of the invention, a milking cup of the above-mentioned type is provided which is characterized by the underpressure relief valve being constructed as a valve connected through a short tube to the suction sleeve and movably supported in the cup. The valve movement corresponds with the movement of the suction sleeve and can be controlled by the pressure difference which exists between the inside of the suction sleeve on one side and the space between cup and suction sleeve on the other side, which in open condition connects these two spaces with one another. The connecting tube between suction sleeve and underpressure relief valve can in this case be kept especially short. Moreover, the tube can be connected releasably to the suction sleeve and can terminate perpendicularly into same. However, additionally it is possible to provide a drip projection which projects into the suction sleeve and which practically makes it impossible for milk to flow back into the pipeline. Since the valve and also the tube lie, in this case, completely within the cup, the valve and also the tube are both protected from damages.
As a protection for the pressure relief valve and at the same time as a cover for the cup, a transparent cap can be provided which closes off the opening in which the pressure relief valve is mounted. Both the operation of the valve and also, for example, the degree of dirt accumulating in an air filter in front of the underpressure relief valve can be precisely observed through the cap.
A characteristic of the present invention consists mainly in underpressure relief air being able to be supplied directly below the tip of the teat.
One preferable embodiment is the provision of an underpressure relief valve which consists of a valve that can be controlled by the difference pressure existing between the inner space between the cup and the suction sleeve on one side, and the tube on the other side, and which, in open condition, connects the tube to the atmosphere. Such a valve can be adjusted such that it opens and closes precisely at different pressures. Such a valve permits in particular a sudden opening and closing.
If one, however, rather uses an underpressure relief valve which consists of a valve which can be controlled by the pressure difference between the inner space between the cup and the suction sleeve on one side, and the tube on the other side, and connects, in open condition, the tube to the pulsator supply pipe, the advantage is obtained that the pulsator air is used directly as relief air and this air can be cleaned specially.